肥大したfilum terminaleを合併した脊髄硬膜内クモ膜のう胞の1例

Spinal Intradural Arachnoid Cyst Associated with Enlarged Filum Terminale

I．はじめに

　脊髄クモ膜のう胞は，脊髄クモ膜憩室とも呼ばれ比較的稀な疾患である^6）．今回われわれは肥大した脊髄終糸を伴い神経放射線学上，硬膜外病変の所見を示しながら実際には脊髄硬膜内クモ膜のう胞であったChiari奇形Ⅰ型の症例を経験したので報告する．

This is a report of a spinal intradural arachnoid cyst associated with an enlarged filum terminale.

A 9-year-old female was admitted to our hospital complaining of lumbosacral pain. Neurological ex-amination revealed no abnormal findings. CT scan showed a round shaped mass lesion in the right dorso-lateral side of the spinal canal between the level of L1 to S1/2. The mass lesion disclosed isodensity and was not enhanced. A small low density mass lesion was visualized in the dural sac at the same level.

MRI showed the mass lesion with low signal intensi-ty on the T1-weighted image, and high signal intensity on the T2. The small mass lesion in the dural sac was demonstrated with low signal intensity on the T1 and T2-weighted image.

In addition to this finding, Chiari malformation type I was disclosed. It was suspected that this mass lesion was extradural arachnoid cyst associated with an en-larged filum terminale.

Osteoplastic laminotomy between L3 to S1/2 was performed, and an arachnoid cyst was found in the in-tradural space. It compressed the cauda equina and en-larged tough filum terminale. The cyst was removed subtotally, and the filum terminale was cut off. Postop-erative course was uneventful and the lumbosacral pain disappeared. It was thought that this pain might be de-rived from the intradural arachnoid cyst, or the en-larged filum terminale. Also it was possible that the compression of the intradural arachnoid cyst might dis-turb the normal elasticity and mobility of the filum ter-minale.

Also, it is considered that spinal arachnoid cyst might be associated with another CNS anomaly, and the treatment of the arachnoid cyst should be reviewed.